Gas and air mixing apparatus



G. KEITH GAS AND AIR MIXING APPARATUS July 6 1926.

s sheets-sheet 1 Filed Sept. 25, 1924 J as QZM OJQIQ,

a (PM July 6 1926.

G. KEITH GAS AND AIR MIXING APPARATUS 7 Filed Sept. 23, 1924 3 Sheets-Shoot 2 2 raw am a G. KEITH GAS AND AIR MIXING APPARATUS July 6 1926.

s Sheets-She d 5 Filed Sept. 23, 1924 v PM! July 6, 1926.

A uN rE-n STATES PATENT OFFICE.

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Application fled septem b'er 2:, 1924, Serial r... ream, and in arm Britain September 25, iaas.

This invention relates to gas and air mix- .ing apparatus designed to meet the demand for the supply: of a pre-formed self burning mixture to a number of burners, as, for 6 example, the burners of bread and biscuit gas-fired ovens. p Problems to be solved are the protection ofthe parts of the apparatus and its suro explosion andconsequences ofpossibleexplosion due to back? firing, for example, and automatic regulation I v of the quality, quantity and pressure of the mixture to be supplied to the. burners. v 7, These problems aresolved by the ap aratus of the invention,- as will hereina r.

- e gas may be-from any source,it being understood that the optimum proportions of as and air will depend on the quality of thegas',

The gas and air; may both be compressed, in which event separate compressing means are employed, so that no'explosion of mix ture can take place in the compressing apparatus; desirably the pressures to which the two constituents. of the mixture are brought exceed the pressure of the mixture. The gas and .air are led throu h pipes,

' one terminating in a nozzle ,and t e, other in a difiusion tube into which the nozzle 'opens. For the purpose of the present dev scription we shall assume that the air is 1 led to the nozzle and the gas to. thetube. The nozzle is arranged in alignment with '33 the diffusion tube in which the air and gas are mixed and from which the mixture passes into a distribution chamber. 5

- The admission of air to the nozzle is controlled by a valve, sucha's a piston valve,

7 fitted to the compressed air supp ly pipe. 'Between'the compremd-gassu p y pipe and the difiusionttube is inte a governor whichserves to govern t e pressure of the gas on its outlet side so that it is equal to the pressure set up in a pipe leading from,

the governor to apo nt sub ect to the pres sure prevailing in the distri ution chamber.

For transmitting movement to thepiston valve there is connected thereto a rod which may extehd through the diffusion tube and through the nozzle'and'which is connected to a controllingdiaphrag'm or the like.

.The controlling diaphragm is fitted within a chamber the unders'i'de. of. which has' a tubular connection w th the compressed air supply i the air ressure acting on the undersi e i f" the di phragm to hold the valve in raised, that is open, position.

' The invention further provides means hereinafter described for effecting regulation of the air pressure acting on the diaphragm.

In the accompanying drawings Fig. 1 is afldiagrammatic sectional elevation of an apparatus embodying .the invention, in which the device for controlling the mixture pressure is set for medium pressure. Fig. 2 is a detached viewfof said device set for minimum pressure; Fig. 3 is a view showing an automatic device for controlling the pressure. Figs'. 4 and 5 are. elevations, partly in section, at right aiigles to each other showing a device for cutting ofi the gas supply automaticall in the event of explosion. Fig. 6'is a ragmentary detail view in section of the controlling diaphragm and chamber. v

4 denotesa nozzle to which air underpressure 'is led through pipes."-

The nozzle 4 is arranged in alignment with a Venturi tube 5 in which the air is mixed with gas ledthrbugh the pipe 3 and from which the mixture asses intoa distribution chamber 6 pi r to the burners 7 p The admission of air is controlled by a valve 8 located behind .thenozzle 4.

Fitted to the gas-supply 2 behind the Venturi-tube 5 is a governor 9 which serves to govern the pressure of the gas on its outlet side so that it is equal to the pressure set up in the pipe IOleading from the governor to the upper compartment of a diaphragm chamber 14 hereinafter referred to. Fitted in the pipe 2 between the governor .outlet and the Venturi-tube, 5 is an adjustable obturator 11, the adjustment of which determines the proportions of gas and air in the final mixture, the control of the proportionment being eflected on the principle disclosed in the specification of Letters Patent No. 1,250,319. 1 i

The regulation of the final ressure of the mixture is determined by t e valve 8, it being understood that when the mixture pressure exceeds a predetermined-amount the valve 8 is caused to obstruct more or less the passagefor the air, resulting in reduction of the pressure in the nozzle 4- and thus neutralizing increase of the ressu-re in the mixture, 'that-in e event of re- 3 ductionof the mixture die to n creased demand, the valve 8 is caused to uncover the air passage until equilibrium is established.

For transmitting movement to the valve 8 there is connected thereto a tubular rod ing on the underside of the diaphragm 131:0

hold the valve 8 in raised, that is open, position in opposition to the spring 8.

. .At any suitable distance from the diaphragm chamberis a tank 18 which is filled with liquid'.say oilup to the level of an overflow 19. In this tank dips a float chamber 20 closed on top and having an opening 7 at or near the bottom, said float chamber 20 enclosing .a float 21 havin'g'a stem 22 con-M nected toope rate a valve 23 on the top of the float chamber. A tube 24 led to the top of the float chamber 20 connects the said chamber 20 with the underside of the diaphragm chamber 14. Within the tank 18, alongside the float chamber 20, is a displacer 25 fitted with a handle 26 which projects to,

the outside of the tank 18 and'by the manipulation of which the liquid level in the tank '18 may be varied between a fixed and a fixed maximum above the level sufficient to sustain the float 21.

- As the float chamber 20 receives compressed air from the diaphragm chamber 14,

the pressure in the float chamber 20 rises until the liquid level in the float chamber 20is depressed below that requisite to sustain the float 21, whereupon the valve 23 begins to open and blow ofl air, preventing further depression of the liquid level in the float chamber 20.

As evidently the air pressure required to be set up in the float chamber 20 to produce this condition of equilibrium will de; pend on the liquid level in the tank 18 outside the float chamber 20 asdetermined by the adjustment of the displacer 25, the invention provides a very accurate and sensitive safety valve device of which the blowing ofl polnt can be varied at will, and which cannot 'be under-loadedor over-loaded.

Alternatively, theliquid level or head in the tank 18 may be varied automatically by employment of a thermostat 27 as-shown in Fig. 3. In'the arrangement shown in Fig. 3 there isarranged adjacent to, the float chamber 20' and desirably enclosed or partly enclosed within the tank 18 a closed vessel 28 the lower .end of which is piped to the tank 18' below the liquid level in the latter, and the upper end of which is connect d with the compressed air supply pipe 2 by a branch 29 from the tube 15, the branch 29', I having a constriction which limits the rate of flow of air. Coupled to the branch 29 is a leaka e tube30 havin an outlet controlled to by the t ermostat 27 an S0 dimensioned that .when the liquid stands at the same level in the closed vessel 28 and in. the tankf18', that'level will be at the desired height above the level in the float chamber 20' requisite to sustain. the float 21'. I 35 To protect the diaphragm 31 of the over-v nor 9 from the consequences of possib e ex- 7 plosion, the spindle 32 connected to the diaphragm 31 is led tlirou h a floating washer 33 which prevents su den inrush. ofrgas W into the diaphragm chamber 34.

For the like reason, there is fitted at the junction of the pipe 10 and the diaphragm chamber 34 a ball valve 35 arranged to.close but movable in opposition to the spring into engagement with its seat when sub ected-to a heavy surge of back-pressure. In order to prevent the possibility'of' an explosion inthe upper compartment of the 1 diaphragm chamber 14 and further to protect the diaphragm 13 from the eflects of an explosion of the main body of. the mixture,- a stream of air led from a point between the valve 8 and the nozzle 4 is allowed to flow -g through -the upper compartment of the dia. phragm chamber 14 and thence into the distribution chamber 6 by way of a small pol-t fitted with a ball valve 17 which will close on a sudden rush of pressure. For leading '5 the air to the said upper compartment the rod 12 is formed tubular-and formed'with a port in its lateral wall as indicated at 12',

the bore of the rod 12 forming an air conv duit which opens at 12 into the upper comport and therefore the downward pressure on the diaphragm 13 is the same as exists in th dl tribution chamber-6.

.. controlling the passage of the first constitucut to' said nozzle, a diaphragm exposed on As the port 12' is located between the valve' 8 and the nozzle 4:, the flow of airthrough the upper com artment of the dia phragm chamber 14-wil always-be exactly proportionate to the volume of mixture. being used, and the regular quality of the'mixture will not be afiected thereby. Q

*As' an additional protection against th consequences of explosion. we providefor cutting 0a the gas entirely-when explosion occurs andthus avoid the possibility of mixture continuing toburn ins'ide'the piping system or escaping at, any point. With this object there is fitted in the. gas supplypipe 2 a self-closing-valv'e, which is allowed to close on operation of a trip 38 efiected by pressure due to an exploslon acting on at spring-loaded piston 39 which is movable id a chamber 40 piped to the distribution chamher 6 and which is operatively connected to the trip 38.

What I claim is 1. Gas and air mixing apparatus, comprising,-in combination, a nozzle, a difiusion tube into which said nozzle opens, a conduit for the passage to said nozzle of one constituent of the gas and air mixture, a conduit for the passage to said-tube of the other constituent of the mixture, agovernor -for governing the pressure of the second constituent, a. valve one side to regulate fluid pressure and on the other side to the pressureof the mixture, and a rod extending through said tube and connecting said diaphragm with said valve.

2. Gas and air mixing apparatus comprising, in combination, a nozzle, a diffusion tube into which said nozzle opens, a connection .for conducting to said nozzle one constituent of the gas and air mixture, a connection for conducting to said tube the 'other'constituent of the mixture, '11 distribution chamber connected to said tube, a governor for governing the pressure of the second constituent, a valve controlling the passa e of the first constituent throughsaid nozz e, a diaphragm chamber having one sidein communication .with said distributio chamber, a diaphragm in said diaphragm chamber, a

connection forpressu're fluid to the other side of said diaphragm,chamber, and a 'rod extending through .said distribution cha m her and said tube and connecting said dia phragm and said valve.

' 3. ,Ga'sand air mixing apparatus comprising, in combination, a nozzle, a difiusion member intowhich said nozzle opens, a connectionfor conducting to said nozzle one constituent of the gas and airmixture, a

connection for conducting to said difiusron member the other constituent'of the inixture, a governor-including): chamber and a diaphragm insaid cham r for governing the pressure otthe constituent conducted .phragm chamber, a tubular connection between said side of said diaphragmcham ber and the chamber of said governor, 'a con-. nection for pressure fluid to .the other side of said diaphragm chamber, and an operative connection between said second mentioned diaphragm and said valve. 1

4.. Gas and air mixing apparatuscomprising, in combination, a nozzle, a diffusion member into which s'aid nozzle opens, a tubular connection for conducting to said nozzle one constituent of the mixture, a tubular connection for'conducting to said difl:'usion member the other constituent of the mixture, a governor for governing the pressure of the constituent conducted through said second tubular connection, a valve controlling the I passage of the first constituent through said I nozzle, a diaphragm chamber having. one side in communicationwith said difiusion member, a diaphragm in said dia hragm chamber, a connection between the ot er side of said diaphragm chamber and. the first tubular connection and, an operative connection between said diaphragm and said valve.

5. Gas and "air mixing apparatus comprising, in combination, a nozzle, a difiusion'tub'e 1 into which said nozzle opens, a connection for cofiducting. to said ,nozzle one constituent of the mixture, a connection for conducting to said tube the other constituent of the mixture, 5. distribution chamber connected her having one side. in' communication with said distribution chamber, a diaphragm in c,

said diaphragm chamber, a tubular connection between said side of said diaphragm chamber and the chamber of said governor, a connection. for pressure fluidto the'othci' side of, said diaphragmchamber, and an op- 'erative connection between said second diaphragm and said valve. I

6-.-Gas and air mixing a paratus' comprising, in combination, a nozz e, a diffusion tube into which said nozzle opens, a connection for conducting to said nozzle one constituent of the mixture, a connection for conducting to said tn be the other constituent of the f mixture, a distribution chamber connected to said tube, a governor for governing the pressurejof the second constituent conducted by said second connectiom-a valve control ling'the passage of the first constituent through said nozzle, a diaphragm chamber h vi ide in communication with said 1 her and the chamber of said governor,- anddistribution chamber, a' diaphragm insaid diaphragm chamber, a tubular connection between' said side of. said diaphragm chama" rod extending th'rough I said distribution chamber'and through said tube and, connecting said diaphragm and said valve. v

7. Gasand air mixing apparatus compi'is ing, in combination, 'a nozzle," a tubu-v lar connection serving to conduct to said nozzlefone .constituent of the mixture, a

tubular connection serving to conduct to said diffusion member the other constituent of the mixture, a governor for governing the pressure of the constituent conducted by said second tubular connection, a valve control ling the passage; of the first constituent through said nozzle, a diaphragm chamber having one side in communication with said difl'usion member, a diaphragm, in said diaphragm chamber, a float chamber in communicationwith the other side of saiddiafor relieving pressure in said float chamber,

' hr gm hamber, said float'chamber having an opening in its bottom wall, a float in said chamber, a tank into which said float dips,

means dependent onthe position of said float and'an operative connection between said diaphragm and said valve.

8. Gas and air mix ng. apparatus, comprismg, In combination, a coaxial nozzleand a diffusion tube, a tubularconnection' servin to conduct to said nozzle one constituent o =chamber','a' float chamber in communication a the mixture, a tubular connection servingto conduct to ,Sflid tube the other constituent of the mixture, a governor for governing the pressure of the'second constituent, a valve controlling the (passage of the first-constituent through sai nozzle, a diaphragm chamher having one side in communication with said tube, a diaphragm in said diaphragm with the other side of, said diaphragm chamher, said ,floatcha mber having an opening in its bottom wall, a float in said float cham her, a gflo'at controlled blow-01f valve fitted toisaid float chamber, aj lj uid-containing tank into which said float camber dips, a displacer' in saidtank adjustable to vary' the blow-ofi pressure, afnd'an operative connection between said diaphragm and said valve. p

, 9. Gas and air IIllXlllg apparatus comprising, in combination, a coaxial nozzle and diffusion tube, a tubular connection serving to conduct to said nozzle one constituent of the mixture, a tubular connection. serving to conduct to" said tube the other constituent of the mixture,'a governor for. overning the pressure of the constituent con noted by said second mentioned tubular conniection, a 'valve controlling the passage of he first constituent through said nozzle, a diaphragm chamber having one side in communication with said tube, a diaphragm in GI said diaphragm chamber, a connection for pressure flui to the other side of said diaphragm chamber, protecting means for preventing possibility of explosion in the first side pf said diaphragmchamber, and an -operative connection between said diaphragm and said valve;

' 10. Gas and air mixing apparatus, comprising, in combination, a diffusion tube, a

conduit leading to said tube one constitu- 7 out of the gas and air mixture, a suction conduit leading to said tube the second constituent of the mixture, a governor for gov- .erning the pressure of the second constitu cut, a valve controlling the admission of the B first constituent to said tube, a diaphragm exposed on one side to regulated fluid pressure and on the other side to the pressure of the mixture, and a mechanical connection extending through said tube andconnecting said diaphragm with said valve.

11. Gas and air mixing apparatus comprising, in combination, a diffusion tube, an orifice for an inducing medium forming one constituent o'f-the mixture, an orifice for an induced medium forming the otherconstitu- .ent' of the mixture, said orifices opening into said tube, separate tubular connections for conducting said media to said orifices, a distribution chamber connected to said 'tube, a governor for governing the pressure of the induced medium, a valve controlling the passage of the inducing medium through the first orifice, a diaphragm chamber having one side in communication withsaid distribution chamber, a diaphragm in said diaphragm chamber, a connection for pressure fluid to the other side of said diaphragm chamber, and a-rod extending-through said distribution chamber and said tube and conectin said diaphragm and'said valve. n "12. as and air mixing apparatus comprising, in combination, a difl'usion tube, separate connections for conducting to said 'tube the constituents of the gas and air mix- 'ture,'a governor including a chamber and a- In testimony-whereof I have signed name to this specification.

GEORGE KEITH. 

